Right ventricular obstruction resulting from anomalous muscle bundles

Abstract

Summary Significant right ventricular outflow obstruction may result from large anomalous muscle bundles traversing the right ventricular cavity. These bundles are located below the infundibulum and are distinct from the trabecula septomarginalis and the moderator band. This type of obstruction may occur independently and is anatomically distinguishable from the more common types of infundibular stenosis. Eleven patients with intact septa and anomalous muscle bundle obstruction to right ventricular outflow are presented. In 5 patients, these bundles represented the only cardiac abnormality and were the sole cause of obstruction to blood flow; while in the remaining 6 patients there was an associated pulmonary valvular stenosis. Cardiac catheterization and angiocardiography provided the correct diagnosis in all cases. Eight patients have undergone operation and all have since been asymptomatic. The authors acknowledge with appreciation Dr. James H. Moller’s courtesy in providing us the opportunity to review Case 11.